U.S. patent number 7,551,244 [Application Number 11/510,001] was granted by the patent office on 2009-06-23 for optical element, light source unit, and display device.
This patent grant is currently assigned to NEC Corporation, NEC LCD Technologies, Ltd., SEIKO Company, Ltd.. Invention is credited to Yoshiaki Furuya, Shigetoshi Hayata, Katsuhisa Ishii, Takahiko Kanamori, Kouji Mimura, Fujio Okumura, Youhei Saitou, Ken Sumiyoshi, Tamio Uchino.
United States Patent |
7,551,244 |
Mimura , et al. |
June 23, 2009 |
**Please see images for:
( Certificate of Correction ) ** |
Optical element, light source unit, and display device
Abstract
An optical element comprises a pair of substrates each having an
electrode and bonded together with a gap therebetween and a light
adjusting material including a liquid crystal and enclosed in the
gap. Each of the pair of substrates has an electrode connecting
portion to be connected to an external circuit. At least a part of
the electrode connecting portion of each of the substrates is
located on the same side as that of the optical element. The
electrode connecting portion of one of the substrates and the
electrode connecting portion of the other of the substrates have
respective electrode portions at regions that are not opposed to
each other. The electrode portion of each of the electrode
connecting portions is connected to the external circuit.
Inventors: |
Mimura; Kouji (Tokyo,
JP), Sumiyoshi; Ken (Tokyo, JP), Okumura;
Fujio (Tokyo, JP), Hayata; Shigetoshi (Fukuoka,
JP), Uchino; Tamio (Fukuoka, JP), Furuya;
Yoshiaki (Fukuoka, JP), Saitou; Youhei (Fukuoka,
JP), Ishii; Katsuhisa (Fukuoka, JP),
Kanamori; Takahiko (Fukuoka, JP) |
Assignee: |
NEC Corporation (Tokyo,
JP)
NEC LCD Technologies, Ltd. (Kanagawa, JP)
SEIKO Company, Ltd. (Fukuoka, JP)
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Family
ID: |
37778385 |
Appl.
No.: |
11/510,001 |
Filed: |
August 25, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070097290 A1 |
May 3, 2007 |
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Foreign Application Priority Data
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Aug 25, 2005 [JP] |
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2005-244159 |
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Current U.S.
Class: |
349/69; 349/61;
349/21; 349/158; 349/151; 349/143; 349/142; 349/139; 349/129;
349/128 |
Current CPC
Class: |
G02F
1/133524 (20130101); G02F 1/13452 (20130101); G02F
1/133606 (20130101); G02F 1/133607 (20210101) |
Current International
Class: |
G02F
1/1335 (20060101); G02F 1/133 (20060101); G02F
1/1333 (20060101); G02F 1/1337 (20060101); G02F
1/1343 (20060101); G02F 1/1345 (20060101) |
Field of
Search: |
;349/21,61,128,129,139,142,143,151,158 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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9-197405 |
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Jul 1997 |
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JP |
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10-173304 |
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Jun 1998 |
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JP |
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2000-111936 |
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Apr 2000 |
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JP |
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2001-242799 |
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Sep 2001 |
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JP |
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2001-356360 |
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Dec 2001 |
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JP |
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2003-270656 |
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Sep 2003 |
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JP |
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Primary Examiner: Peng; Charlie
Assistant Examiner: Lam; Hung
Attorney, Agent or Firm: Scully, Scott, Murphy &
Presser, P.C.
Claims
What is claimed is:
1. An optical element, comprising: a pair of substrates each having
an electrode, the pair of substrates being bonded together with a
gap formed therebetween, each of the pair of substrates having an
electrode connecting portion for connecting the respective
substrate to an external circuit, the electrode connecting portion
of each of the substrates being located on the same side of the
optical element, the electrode connecting portion of one of the
substrates and the electrode connecting portion of another of the
substrates having respective electrode portions disposed on the
side of each of the substrates facing the gap and on regions that
are not opposed to each other the electrode portion of each of the
electrode connecting portions being connected to the external
circuit; and a light adjusting material including a liquid crystal,
the light adjusting material being enclosed in the gap.
2. The optical element according to claim 1, wherein the electrode
portion is not projected from the side of the optical element.
3. The optical element according to claim 1, wherein the electrode
connecting portion of the one of the substrates and the electrode
connecting portion of the other of the substrates have regions that
are opposed to each other; and wherein the regions that are opposed
to each other are bonded together in at least one part.
4. The optical element according to claim 1, wherein the electrode
portion of each of the electrode connecting portions is connected
to the external circuit through an additional electrode portion,
and a protective film is provided over the region in which the
electrode portion of each of the electrode connecting portions and
the additional electrode portion are not opposed to each other.
5. The optical element according to claim 1, wherein, on one or
each of the pair of substrates, the optical element has an area
without electrode in a part or over the entirety of the periphery
thereof; and wherein the optical element has a layer that bonds
together the pair of the substrates in a part or entirety of the
area and that separates the optical element from the outside.
6. A light source unit comprising: a backlight that emits light; a
light beam direction regulating element that regulates the
direction of light entered from the backlight and that emits the
light; and an optical element, comprising: a pair of substrates
each having an electrode, the pair of substrates being bonded
together with a gap formed therebetween, each of the pair of
substrates having an electrode connecting portion for connecting
the respective substrate to an external circuit, the electrode
connecting portion of each of the substrates being located on a
same side of the optical element, the electrode connecting portion
of one of the substrates and the electrode connecting portion of
another of the substrates having respective electrode portions
disposed on the side of each the substrates facing the gap and on
regions that are not opposed to each other, the electrode portion
of each of the electrode connecting portions being connected to the
external circuit; and a light adjusting material including a liquid
crystal, the light adjusting material being enclosed in the
gap.
7. A display device comprising: a backlight that emits light; a
light beam direction regulating element that regulates the
direction of light entered from the backlight and that emits the
light; an optical element, comprising: a pair of substrates each
having an electrode, the pair of substrates being bonded together
with a gap formed therebetween, each of the pair of substrates
having an electrode connecting portion for connecting the
respective substrate to an external circuit, the electrode
connecting portion of each of the substrates being located on a
same side of the optical element, the electrode connecting portion
of one of the substrates and the electrode connecting portion of
another of the substrates having respective electrode portions
disposed on the side of each the substrates facing the gap and on
regions that are not opposed to each other, the electrode portion
of each of the electrode connecting portions being connected to the
external circuit; and a light adjusting material including a liquid
crystal, the light adjusting material being enclosed in the gap;
and a liquid crystal display element stacked on the optical
element.
8. The optical element as recited in claim 1, wherein the optical
element is incorporated in a terminal device.
9. The light source unit as recited in claim 6, wherein the light
source unit is incorporated in a terminal device.
10. The display device as recited in claim 7, wherein the display
device is incorporated in a terminal device.
Description
This invention claims priority to prior application JP 2005-244159,
the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to an optical element, light source
unit, and display device. More specifically, the present invention
concerns an optical element with a terminal connecting structure,
having an improved yield while ensuring reliability, a light source
unit using this optical element, and a display device equipped with
this light source unit.
Liquid crystal display devices are installed on portable or
hand-held terminals (mobile phones, notebook personal computers,
etc.) and others, and they are in widespread use because of their
features of being thin, lightweight, and low in power consumption.
Such features of the liquid crystal display devices allow hand-held
terminals to be used under various environments.
For example, in some case, the display of a hand-held terminal may
be shared among a plurality of persons in a conference, and in some
case, information may be inputted into the hand-held terminal at a
public place such as an electric train or airplane.
In this way, performance required of the display of hand-held
terminal varies depending on usage environments. For example, in
the former case, since the display is shared among a plurality of
persons, it is desired that the display of hand-held terminal be
visible from anywhere, i.e., the view angle of the display device
be as wide as possible. On the other hand, in the latter case, from
the viewpoint of information conservation and privacy protection,
it is desired that the view angle be no wider than allows user
alone to see the display.
Therefore, it is demanded that the display of hand-held terminal,
especially the view angle can be controlled to vary from a wide
view angle state up to a narrow view angle state in accordance with
a usage environment. A display device meeting this demand is, for
example, disclosed in Japanese Unexamined Patent Application
Publication No. 9-197405 (hereinafter referred to as Patent
Document 1).
FIGS. 1A and 1B each schematically illustrates a conventional
liquid crystal display device set forth in the Patent Document 1,
wherein FIGS. 1A and 1B show a wide view angle state and narrow
view angle state, respectively.
As shown in FIGS. 1A and 1B, the conventional liquid crystal
display device 200 includes a liquid crystal display element 40,
light source 41, first optical element 42 that substantially
collimates light from the light source 41, and second optical
element 43 that electrically controls
diffusion/rectilinear-propagation of light emitted from the first
optical element 42. The liquid crystal display device 200 is
configured so that the light source 41, first optical element 42,
second optical element 43, and liquid crystal display element 40
are stacked in this order from the light source side.
The liquid crystal display device 200 performs switching between a
wide view angle display and narrow view angle display, by
controlling rectilinear-propagation/diffusion of light entering the
liquid crystal display element 40 by the second optical element
43.
In the liquid crystal display device 200 performing switching
between a wide view angle display and narrow view angle display in
this way, at least the optical element 43 must be inserted between
the liquid crystal display element 40 and light source 41.
However, in a mobile phone, since a light source and optical
element are accommodated in a very compact manner, a space for
incorporating therein the optical element 43 is highly limited. In
particular, because the casing trim-like frame (hereinafter
referred to as a frame) of the display portion is very narrow, a
terminal connecting portion between the optical element 43 and an
external circuit for driving the optical element 43 has a
significantly limited space.
In order to insert at least the optical element 43 between the
liquid crystal display element 40 and light source 41, it is
desirable that the optical element 43 be thin and lightweight. A
possible method for reducing the thickness and weight of the
optical element 43 is to use a film as a substrate. In this case,
as in the case of a conventional liquid crystal panel, if a pair of
substrates are opposed, an electrode of one of the substrates is
electrically connected to an electrode of the other of the
substrates via a silver paste, and the one substrate alone is
electrically connected with an external circuit, then the gap in
the silver paste portion increases. This undesirably causes
variations in displays of the optical element 43. Therefore, when
thinned substrates are to be used, it is desirable not to
electrically connect the one substrate alone, but connect both of
the pair of the substrates to the external circuit.
Methods for taking out respective electrodes from both of the pair
of the substrates and connecting them to the external circuit, are
disclosed in Japanese Unexamined Patent Application Publication No.
2001-356360 (hereinafter, Patent Document 2) and Japanese
Unexamined Patent Application Publication No. 10-173304
(hereinafter, Patent Document 3).
The Patent Document 2 sets forth a structure for the connection of
a liquid crystal device with an external circuit.
FIG. 2 is a plan view showing a connection structure between a
liquid crystal device and external circuit, the connection
structure being disclosed in the Patent Document 2. A liquid
crystal panel 1 comprises a first substrate 2, second substrate 3,
and cell constituted of a sealing member (not shown) interposed
between the first and second substrates 2 and 3, the cell being
formed by sealing therein a liquid crystal (not shown). The first
substrate 2 has a first connection portion 2a formed so as to
project from a portion opposed to the second substrate 3. On the
surface of the first connection portion 2a, an electrode pattern
(not shown) is formed and a first integrated circuit 5 is mounted.
The second substrate 3 has a second connection portion 3a formed so
as to project from a portion opposed to the first substrate 2. On
the surface of the second connection portion 3a, there is provided
an electrode pattern (not shown).
A flexible substrate 4 includes a first end portion 4a and second
end portion 4d. On the first end portion 4a, an electrode pattern
and connector portion (neither shown) are formed, and a second
integrated circuit 6 is mounted. An electrode pattern (not shown)
is also formed on the second end portion 4d.
An electrode pattern (not shown) of the flexible substrate 4 is
connected to the first substrate 2, and an electrode pattern (not
shown) of the flexible substrate 4 is also connected to the second
substrate 3. The flexible substrate 4 is substantially orthogonally
folded at a folded portion located at the midway between the first
end portion 4a and second end portion 4d.
On the other hand, the Patent Document 3 discloses a structure for
the connection of a liquid crystal device with a circuit
substrate.
FIG. 3 is a schematic sectional view showing a connection method
for an LCD (liquid crystal display) panel substrate and circuit
substrate (FFC) [flat flexible cable], the connection method being
disclosed in the Patent Document 3. An LCD panel substrate 32
comprises an upper substrate (first substrate) 21 and lower
substrate (second substrate) 22, and liquid crystal (not shown)
interposed therebetween, and seal portion 23 arranged therearound.
A transparent electrode 24 and terminal 28 are formed on the
surface of the upper substrate 21, and a conductive paste 30 is
formed on the surface of the terminal 28. Similarly, a transparent
electrode 25 and terminal 29 are formed on the surface of the lower
substrate 22, and a conductive paste 31 is formed on the surface of
the terminal 29.
Here, the side of the upper substrate 21, to be connected to the
FFC is referred to as an upper tail portion 26, while the side of
the lower substrate 22, to be connected to the FFC is referred to
as a lower tail portion 27.
For the connection between the LCD panel substrate and FFC, firstly
the upper substrate 21 and lower substrate 22 are pinched and fixed
by a pinching member 20 using seal portion 23 on the sides of the
upper tail portion 26 and lower tail portion 27. Then, a jig 15
having therein an opening 16 is inserted between the upper and
lower tail portions 26 and 27; the space between the upper tail
portion 26 and lower tail portion 27 is opened up; and a connecting
terminal 13 of the FFC 10 is inserted into the opening 16. The
connecting terminal 13 is covered with a covering material 12. By
heating and fusing conductive pastes 30 and 31 that have been
coated and hardened on the terminals 28 and 29, respectively, the
terminal 28 of the upper tail portion 26, the terminal 29 of the
lower tail portion 27, and the connecting portion 13 of the FFC 10
can be connected. Then, the LCD panel 32 and FFC 10 are bonded
together with an adhesive tape. Thereafter, the pinching member 20
is removed and the jig 15 is removed through the opening 16 of the
FFC 10.
However, the above-described conventional arts involve the
following problems.
In the liquid crystal device set forth in the Patent Document 2,
the taking out of electrodes in the first and second substrates is
performed from two sides of the liquid crystal device. However,
this undesirably widens the frame of the sides for taking out the
electrode. In particular, when the liquid crystal device is
incorporated into a mobile phone, a light source or optical element
is accommodated in a very compact manner. As a result, the space
for accommodating the optical element 43 is so small that the
connection with the outside is performed by substantially one side.
If the structure of the device is left unchanged, the connection
with an external circuit for driving the optical element 43 would
be impossible.
In the liquid crystal display device set forth in the Patent
Document 3, it is attempted to establish the connection with the
external circuit by opening a part of the device. However, in the
case where the connecting portion with the external circuit is very
narrow as in the mobile phone, there is no space for create a
margin for opening. As a result, when terminals are joined to each
other, there occurs seal peeling in the vicinity of the opening
portion, resulting in a reduction in yield. Also, since the
terminal is sandwiched between the upper tail portion and lower
tail portion, the gap in the vicinity of the terminal connection
portion increases by the thickness of the terminal. Hence, it is
difficult to control the gap in the display surface, resulting in
occurrences of variations in display. Furthermore, because of the
structure such that the terminal is sandwiched between the upper
and lower substrates, electrode portions near the seal material
must be exposed. As a consequence, there occurs a possibility that
a short circuit between electrodes will takes place and that the
electrodes will become corroded because of adhesion of water or the
like.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an
optical element allowing the above-described problems to be
solved.
To solve the above-described object, we have carried out researches
and obtained the conclusions described hereinafter.
According to a first aspect of the present invention an optical
element is provided. In the optical element, a pair of substrates
each having an electrode is bonded together with a gap
therebetween, and a light adjusting material including a liquid
crystal is enclosed in the gap. Each of the pair of substrates has
an electrode connecting portion to be connected to an external
circuit. At least a part of the electrode connecting portion of
each of the substrates is located on the same side as that of the
optical element. The electrode connecting portion of one of the
substrates and the electrode connecting portion of the other of the
substrates have respective electrode portions at regions that are
not opposed to each other. The electrode portion of each of the
electrode connecting portions is connected to the external
circuit.
Since the optical element according to the first aspect is
configured so that the electrode connecting portion on one
substrate and that on the other substrate do not superimpose on
each other, the terminal can be connected without the need to open
the terminal connecting portions, unlike the case of the Patent
Document 2. This allows the suppression of yield reduction of the
optical element due to seal peeling when performing terminal
connection. Furthermore, since the terminal connection can be
established without the need to open terminal connecting portions,
it is possible to reduce a margin on the seal side of the opening
portion for terminal connection, leading to the narrowing of the
frame of sides of the terminal connecting portions. Furthermore,
since the terminal connection is feasible without the use of a
pinching member or a jig for terminal insertion unlike the
conventional art, work efficiency is improved. Moreover, since the
electrode connecting portion of one substrate and that of the other
substrate are not superimposed on each other, there is no need for
the connection terminal to be pinched by a pair of substrates,
thereby eliminating a gap defect of the optical element due to the
thickness of the connection terminal.
As is evident from the foregoing, the optical element according to
the first aspect allows its yield to be improved while ensuring its
reliability, and further can be held in a space-saving manner.
An optical element according to a second aspect is characterized in
that an electrode portion does not project from a side of the
optical element. That is, in the optical element according to the
second aspect, a side of the electrode connecting portion including
the electrode portion of the optical element and connecting with an
external circuit, substantially does not project. Therefore, even
if a local force, such as tensile force with respect to the
connection terminal with the external circuit, is applied to the
electrode portion, the applied force can be dispersed by virtue of
the existence of the electrode connecting portions other than the
electrode portion. This prevents an optical element defect due to
seal peeling in the vicinity of the electrode portion.
Furthermore, when the optical element according to the second
aspect is mounted as a component of a light source unit or display
device, the present optical element may be bonded to each of the
light beam direction regulating element and liquid crystal display
device with a double-faced tape. In this case, by causing the
electrode connecting portions including the electrode portion to
have a structure existing over one entire side of the optical
element, it is possible to gain adhesion areas with the light beam
direction regulating element and liquid crystal display device.
Hence, even if shocks or vibrations are applied to the light source
unit or display device, there occurs no seal peeling, thereby
enabling the defect prevention of the light source unit and display
device.
In an optical element according to a third aspect of the present
invention, the electrode connecting portion of the one of the
substrates and the electrode connecting portion of the other of the
substrates have regions that are opposed to each other. The regions
that are opposed to each other are bonded together in at least one
part.
The difference of the optical element according to the third aspect
from that according to the first aspect lies in that the region
where a connection terminal for external connection and the
electrode portion on one electrode connecting portion are
connected, and the region where the connection terminal for
external connection and the electrode portion on the other
electrode connecting portion are connected, exclusively, are not
superimposed on each other. Hence, the area of one electrode
connecting portion and the area of the other electrode connecting
portion each of which is not connected to a respective one of the
connection terminals, are opposed to each other. On those areas,
there are provided bonding layers for bonding together the one and
other electrode connecting portions. With such an arrangement, the
present invention produces the effect of increasing the bonding
strength of a side including the one and the other electrode
connecting portions of the optical element. Furthermore, since the
area of the one electrode connecting portion, to be connected to an
external circuit, and area of the other electrode connecting
portion, to be connected to the external circuit, are not opposed
to each other, it is possible to enhance the yield of the optical
element while ensuring its reliability, and further hold the
optical element in a space-saving manner, as in the case of the
optical element according to the first aspect.
In an optical element according to a fourth aspect of the present
invention, the electrode portion of each of the electrode
connecting portions is connected to the external circuit through an
additional electrode portion, and a protective film is provided
over the region in which the electrode portion of each of the
electrode connecting portions and the additional electrode protion
are not opposed to each other.
The optical element according to the fourth aspect can solve the
problem that, even if the electrode portion on the one electrode
connecting portion and that on the other electrode connecting
portion are electrically connected to the connection terminal for
external connection, the electrode portions and electrodes in the
vicinity of seal will be exposed. Specifically, with the structure
according to the fourth aspect, the present invention allows a
protective film for short circuit prevention and/or corrosion
protection to be formed over exposed portions of electrodes since
they are not covered with both substrates unlike the conventional
example, even if there are the exposed portions of electrodes left.
Therefore, with the structure according to the fourth aspect, it is
possible to reliably achieve short circuit prevention and corrosion
protection.
In an optical element according to a fifth aspect of the present
invention, on one or each of the pair of substrates, the optical
element has an area without electrode in a part or over the
entirety of the periphery thereof. The optical element has a layer
that bonds together the pair of the substrates in a part or
entirety of the area and that separates the optical element from
the outside.
As in the optical element according to the fifth aspect, by
providing an area without electrode on a part or over the entirety
of the peripheral region of one or each of the substrates, the
entire optical element portion according to the fifth aspect,
bordering on the outside, becomes an insulating layer. This allows
an increase in an adhesion force between sealing material for
bonding together the upper and lower substrates, and the upper and
lower substrates, leading to an improvement in yield of the optical
element. Moreover, the electrodes are not located on the outermost
periphery of the substrate, and hence, for example, even if
conductive matter such as water drops adheres to the end portions
of the upper and lower substrates, there is no possibility of
causing a short circuit. This produces the effect of preventing an
optical element defect.
A light source unit according to a sixth aspect of the present
invention comprises a backlight that emits light, a light beam
direction regulating element that regulates the direction of light
entered from the backlight and that emits the light. The light
source unit further comprises the optical element according to any
one of the first to fifth aspect. The optical element is stacked on
the light beam direction regulating element.
With such a stacked structure, the present invention allows the
optical element to be held in a narrow space, while increasing its
yield.
Furthermore, use of the optical element formed by enclosing a light
adjusting material made by mixing a liquid crystal and polymer
material into the gap between the two substrates, enables switching
the optical element between a transparent state and scattering
state by the switching between the state of applying a voltage to
the optical element through the external circuit and the state of
not doing so. This produces the effect of making variable the
lighting angle range of the light source unit.
A display device according to a seventh aspect of the present
invention comprises a backlight that emits light, a light beam
direction regulating element that regulates the direction of light
entered from the backlight and that emits the light. The display
device further comprises the optical element according any one of
the first to fifth aspects. The optical element is stacked on the
light beam direction regulating element. The display device still
further comprises a liquid crystal display element stacked on the
optical element.
With such a feature, it is possible to held the optical element in
a narrow space while improving its yield. Furthermore, since it is
possible to switch the optical element between a transparent state
and scattering state by the switching between the state of applying
a voltage to the optical element through the external circuit and
the state of not doing so, whereby the lighting angle range of the
light source unit can be made variable. This allows a display
device that can be switched between a wide view angle display and
narrow view angle display to be provided.
A terminal device according to the present invention is
characterized by being equipped with the above-described optical
element, a light source unit using this optical element, or a
display device using this light source unit. This makes it possible
to held the optical element in a narrow space while enhancing yield
thereof, as well as to make variable the lighting angle range of
the light source unit. Furthermore, in the liquid crystal display
element, its light source unit has a variable lighting angle range,
the switching between a wide view angle display and narrow angle
display can be achieved. Moreover, the terminal device equipped
with this liquid crystal element device allows privacy protection,
data conservation, and the sharing of display, since the selection
between a wide view angle display and narrow view angle display can
be made in accordance with a usage environment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B are schematic diagrams of a liquid crystal device
according to a first conventional example;
FIG. 2 is a schematic diagram of a liquid crystal device according
to a second conventional example;
FIG. 3 is a schematic diagram of a liquid crystal device according
to a third conventional example;
FIG. 4 is a plan view of an optical element according to a first
embodiment of the present invention.
FIG. 5 is a sectional view taken along a line A-A' in FIG. 4.
FIG. 6A is a plan view of an optical element according to a second
embodiment of the present invention.
FIGS. 6B and 6C are each a plan view showing the relationship among
an upper electrode, lower electrode, and transparent electrode
shown in FIG. 6A.
FIG. 7 is a sectional view taken along a line A-A' in FIG. 6A.
FIG. 8 is a plan view of an optical element according to a third
embodiment of the present invention, wherein a portion
corresponding to the vicinity of an electrode connecting portion of
an upper electrode in FIG. 4 is especially shown in enlarged
form.
FIG. 9 is a sectional view of a light source unit according to a
fourth embodiment of the present invention.
FIG. 10 is a sectional view of a display device according to a
fifth embodiment of the present invention.
FIGS. 11A and 11B, respectively, are a sectional view showing a
scattering state and transmission state of the optical element
according to the present invention.
FIG. 12 is an example in which the present invention is
incorporated especially into a mobile phone out of terminal
devices.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
First, an optical element according to a first embodiment of the
present invention will be described with reference to FIG. 4. FIG.
4 is a plan view of the optical element according to the first
embodiment, and FIG. 5 is a sectional view taken along a line A-A'
in FIG. 4. Here, FIGS. 4 and 5 show a requisite minimum structure
alone, for facilitating the understanding of the structure of this
optical element according to this embodiment. The structure,
therefore, is depicted as being somewhat different from the actual
structure.
As shown in FIGS. 4 and 5, in the optical element 100 according to
the first embodiment, an upper substrate 50 and lower substrate 51
are bonded together by a sealing material (not shown) with a gap
therebetween, and a light adjusting material (not shown) made by
mixing a liquid crystal and polymer is enclosed in the gap. In the
first embodiment, although a mixture of a liquid crystal and
polymer is used as the light adjusting material, the liquid crystal
alone may be used as the light adjusting material.
On each of the upper substrate 50 and lower substrate 51, there is
provided a transparent electrode 52 for driving the light adjusting
material.
Electrode connecting portions 53 and 54 for establishing an
electric connection with an external circuit are provided on the
upper substrate 50 and lower substrate 51, respectively. The
electrode connecting portions 53 and 54 are provided on the same
side of the optical element 100, and they are configured so that
they do not project substantially from the side of the optical
element 100, and that they are not opposed to each other.
The transparent electrode 52 on each of the upper substrate 50 and
lower substrate 51 is projected toward a part on a respective one
of the electrode connecting portion 53 and electrode connecting
portion 54 of each of the substrates, and these projected portions
form respective electrode portions 56 and 57 for connecting with an
electrode for an external circuit. The electrode portions 56 and
57, respectively, are electrically connected to electrode portions
(additional electrode portions) 58 and 59 on the connection
terminal 55 that is electrically connected to the external circuit.
The connection terminal 55 is connected to the external circuit
(not shown) so as to be able to apply a drive waveform signal to
the optical element 100 through the electrode portions 58 and
59.
On each of the upper substrate 50 and lower substrate 51, a region
without the transparent electrode 52 is formed around the outer
peripheral portion including the outermost periphery. Furthermore,
a sealing material (not shown) is applied to the region without the
transparent electrode 52 on both substrates, except for the
electrode portions 56 and 57, thereby bonding together the upper
substrate 50 and lower substrate 51.
As described above, in the first embodiment, since the electrode
connecting portion 53 on the upper substrate 50 and the electrode
connecting portion 54 on the lower substrate 51 are not opposed to
each other, the terminal can be connected without the need to open
the terminal connecting portions. This allows the suppression of
yield reduction of the optical element due to seal peeling when
performing terminal connection.
Furthermore, since the terminal connection can be established
without the need to open terminal connecting portions, it is
possible to reduce a margin on the seal side of the opening portion
for terminal connection, leading to the prevention of occurrence of
a short circuit between electrodes or their corrosion due to water
or the like. Also, since the terminal connection is feasible
without the use of a pinching member and/or a jig for terminal
insertion unlike the conventional art, work efficiency is
improved.
Moreover, in the first embodiment, since the electrode connecting
portions 53 and 54 are not opposed to each other, there is no need
for the connection terminal to be pinched by the upper and lower
substrates. This allows a gap defect of the display portion due to
the thickness of the connection terminal 55 to be eliminated.
Furthermore, since the terminal connection can be established
without the need to open terminal connecting portions, there is no
need to provide a margin in the terminal connecting portions for
the purpose of preventing seal peeling. This leads to the narrowing
of the frame of the side of the optical element 100.
By providing an area without electrode on a part or over the
entirety of the peripheral region on both of the upper substrate 50
and lower substrate 51, the entire optical element portion of the
optical element 100, bordering on the outside, becomes an
insulating layer. Moreover, the electrode are not located on the
outermost periphery of the substrate, and hence, for example, even
if conductive matter such as water drops adheres to the end
portions of the upper and lower substrates, there is no possibility
of causing a short circuit. This produces the effect of preventing
an optical element defect.
Since the upper and lower substrates 50 and 51 are bonded together
by interposing the seal member in an area without electrode around
the upper and lower substrates, the adhesion force between the
sealing material and the upper and lower substrates increases,
resulting in an improved yield of the optical element.
Moreover, the electrode connecting portions 53 and 54 are
configured to be formed on the same side of the optical element
100, and not to project from the side of the optical element.
Therefore, even if a local force, such as tensile force with
respect to the connection terminal with the external circuit, is
applied to the electrode portion, the applied force can be
dispersed by virtue of the existence of the electrode connecting
portions 53 and 54 other than the electrode portion. This allows
the prevention of a display defect due to seal peeling in the
vicinity of the electrode portion.
As will be described in detail later with reference to FIGS. 9 and
10, when the optical element 86 is mounted as a component of a
light source unit or display device, the optical element 86 is
bonded to each of the light beam direction regulating element 72
and liquid crystal display device 85 with a double-faced tape, and
fixed. In this case, the electrode connecting portions 53 and 54
including the electrode portions have been caused to have a
structure existing over the one entire side of the optical element
100, it is possible to gain adhesion areas with the light beam
direction regulating element 72 and liquid crystal display device
85. Hence, even if shocks or vibrations are applied to the light
source unit or display device, there occurs no seal peeling,
thereby enabling the defect prevention of the light source unit and
display device.
Here, operations of the optical element 100 according to the first
embodiment will be described.
The drive waveform signal sent from the external circuit is
transmitted to the upper and lower transparent electrodes 52
through the electrode portions 58 and 59 on the connection terminal
55, and drives the light adjusting material.
In the first embodiment, as shown in FIGS. 11A and 11B, a polymer
dispersion liquid crystal layer 75 constituted of a mixture of a
liquid crystal and polymer material is used as a light adjusting
material. The polymer dispersion liquid crystal layer 75 is
sandwiched between electrodes 74 and 76, and further sandwiched
between substrates 73 and 77. The polymer dispersion liquid crystal
layer 75 is configured so that liquid crystal molecules 75b are
dispersed in a droplet form in a polymer film 75a. The refractive
index of the polymer film 75a and the ordinary refractive index of
the liquid crystal molecules 75b are approximately conformed to
each other, and the extraordinary refractive index of the liquid
crystal molecules 75b is higher than the refractive index of the
polymer film 75a.
As shown in FIG. 11A, when no voltage is applied to the electrodes
74 and 76, droplet-shaped liquid crystal molecules 75b are oriented
in random directions since they have been subjected to no
orientation processing. As a result, the refractive index of the
droplet becomes the average value between the ordinary refractive
index of the liquid crystal molecules 75b and the extraordinary
refractive index thereof, thus exceeding the refractive index of
the polymer film 75a. The difference in refractive index between
the droplet and polymer film 75a brings the polymer dispersion
liquid crystal layer 75 into a scattering state. Because the
difference in refractive index is not anisotropy, light is
isotropically scattered.
On the other hand, as shown in FIG. 11B, upon application of a
voltage to the electrodes 74 and 76, the liquid crystal molecules
75b in the droplets are oriented in the direction of an electric
field. That is, the major axes (having a direction of extraordinary
refractive index) of the liquid crystal molecules 75b are aligned
with one another in the direction parallel to the element normal
direction (in the upward direction in the drawing). In the element
surface, therefore, the refractive index of the liquid crystal
molecules 75b becomes the ordinary refractive index thereof, thus
conforming to the refractive index of the polymer film 75a. This
brings the polymer dispersion liquid crystal layer 75 into a
transparent state.
As is evident from the foregoing, with the structure according to
the first embodiment, the present invention allows the yield of the
optical element to be enhanced while ensuring its reliability, and
enables the optical element to be stored in a space-saving manner,
as well as it is capable of driving the optical element.
Second Embodiment
Next, a second embodiment according to the present invention will
be described.
FIG. 6A is a plan view of an optical element according to the
second embodiment, and FIGS. 6B and 6C are plan views each showing
the relationship among an upper electrode, lower electrode, and
transparent electrode in this optical element. FIG. 7 is a
sectional view taken along a line A-A' in FIG. 6A. Here, FIGS. 6A
to 6C show its requisite minimum construction alone, for
facilitating the understanding of the structure of the optical
element according to this embodiment. The structure, therefore, is
depicted as being somewhat different from the actual structure.
The difference of the optical element according to the second
embodiment from that of the first embodiment lies in that the
regions where the electrode connecting portions 53 and 54 are not
opposed to each other are set as follows. The region where the
electrode portions 56 and 58 are connected out of the electrode
connecting portion 53, and the region where the electrode portions
57 and 59 are connected out of the electrode connecting portion 54,
are configured so as not to be opposed to each other. As a result,
both side regions (refer to FIG. 6B) of the electrode connecting
portion 53 and both side regions (refer to FIG. 6C) of the
electrode connecting portion 54 are mutually opposed. These opposed
portions are provided with bonding layers 60a and 60b for bonding
the electrode connecting portions 53 and 54, respectively. With
this feature, the present invention produces the effect of
increasing the bonding strength of a side including the electrode
connecting portions 53 and 54 of the optical element.
Since the area of the electrode connecting portion 53, to be
connected to the external circuit and the area of the electrode
connecting portion 54, to be connected to the external circuit are
not opposed to each other, it is possible to improve the yield of
the optical element while ensuring its reliability, and further
held the optical element in a space-saving manner, as in the case
of the optical element according to the first aspect.
Furthermore, constructions, operations, and effects other than the
foregoing in the second embodiment are similar to those in the
above-described first embodiment.
Third Embodiment
Now, an optical element according to a third embodiment of the
present invention will be described.
The optical element according to the third embodiment is
characterized in that: a pair of substrates each having an
electrode is bonded together with a gap therebetween; a light
adjusting material including at least a liquid crystal is enclosed
in the gap; each of the pair of substrates has an electrode
connecting portion to be connected to an external circuit; and a
protective film is provided over at least a part of each of the
regions that include the electrode portion of each of the electrode
connecting portions. That is, the difference of the optical
elements according to the third embodiment from those of the first
and second embodiments lies in that a protective film 56a is formed
over each of the portions in which the electrode portions 56, 57
and the electrode portions 58, 59 are not opposed to each other,
respectively (FIG. 8 shows only a protective film over the portion
in which the electrode portion 56 and the electrode portion 58 is
not opposed to each other).
FIG. 8 is a plan view of the neighborhood of the electrode
connecting portion 53 on the upper substrate 50 in FIG. 4, this
plan view being shown in an enlarged form for exhibiting the
feature of the optical element according to the third embodiment.
As is evident from FIG. 8, the electrode portion 56 projected from
the transparent electrode 52 toward the electrode connecting
portion 53, and the electrode portion 58 of the connection terminal
55 (not shown) are electrically connected to each other.
As shown in FIG. 8, even though the electrode portion 56 on the
electrode connecting portion 53 is electrically connected to the
electrode portion 58 of the connection terminal 55, there is a
possibility that the electrode portion 56 in the vicinity of the
sealed portion will be exposed. However, with a construction such
as that of the third embodiment, even if there are the exposed
portions of electrodes left, the present invention enables a
protective film 56a for short circuit prevention and/or corrosion
protection to be formed over the exposed portions of electrodes
since they are not covered with the upper and lower substrates
unlike the conventional example. Therefore, use of the structure
according to the third embodiment makes it possible to reliably
achieve short circuit prevention and corrosion protection. In
addition, the protective film 56a may be provided so as to cover
each of the whole regions of the electrode portions 56 and 57 as
illustrated by a chain line in FIGS. 7 and 8.
Furthermore, constructions, operations, and effects other than the
foregoing in the third embodiment are similar to those in the
above-described first and second embodiments.
Fourth Embodiment
Next, a light source unit according to a fourth embodiment of the
present invention will be described.
The light source unit according to the fourth embodiment of the
present invention is characterized in that the above-described
optical element is stacked on a backlight that emits light, and a
light beam direction regulating element that regulates the
direction of light incident from the backlight and that emits the
light.
FIG. 9 is a sectional view of the light source unit according to
the fourth embodiment of the present invention. Here, components
are separately illustrated for easy understanding. As shown in FIG.
9, in the light source unit according to the fourth embodiment, the
light beam direction regulating element 72 is provided on the
backlight 70, and the above-described optical element 86 is
provided on the light beam direction regulating element 72. As can
be seen from this construction, the light source unit includes a
light-emitting portion, light beam direction regulating element,
and optical element, and is different from the light source 41
described with reference to FIGS. 1A and 1B. The light source 41
described with reference to FIGS. 1A and 1B corresponds to the
backlight 70 out of the light source unit according to the present
invention.
As shown in FIG. 9, a light source element 70a is provided on a
side of the backlight 70, and causes light emitted from the light
source element 70a incident on a light guide plate 70c. The light
guide plate 70c refracts and makes reflect the incident light to
change the incident angle by a plurality of prisms (not shown)
provided in a plane of the light guide plate 70c and a light
reflector 70b provided on the back thereof, and emits light from
the entire surface of the light guide plate 70c. The outgoing light
has an angular distribution spread at a wide angle about the normal
direction to an element surface (i.e., upward direction in the
drawing, in FIG. 9).
Here, in order to enhance the usage efficiency of the backlight
beams, it is desired to narrow the spread of the backlight beams to
a minimum.
As shown in FIG. 9, the light beam direction regulating element 72
is configured, for example, so that the transparent region 72a that
passes light through and an absorption region 72b that absorbs
light are alternately arranged in a direction parallel to the
surface of the light beam direction regulating element 72 (i.e., in
the right-left direction of the drawing). Out of light outgoing
from the backlight, narrow angle light from the front direction
passes through the transparent region 72a and is emitted. However,
wide angle light cannot pass through the transparent region 72a,
but is absorbed in the absorption region 72b. This restricts the
spread of light of the outgoing light from the backlight 70.
As shown in FIG. 9, the optical element 86 has a structure, for
example, wherein the polymer dispersion liquid crystal layer 75 is
sandwiched between electrodes 74 and 76, and further sandwiched
between substrates 73 and 77. The polymer dispersion liquid crystal
layer 75 is configured so that the liquid crystal molecules 75b are
dispersed in a droplet form in the polymer film 75a. The refractive
index of the polymer film 75a and the ordinary refractive index of
the liquid crystal molecules 75b are approximately conformed to
each other, and the extraordinary refractive index of the liquid
crystal molecules 75b is higher than the refractive index of the
polymer film 75a.
As described with reference to FIG. 11A, when no voltage is
applied, droplet-shaped liquid crystal molecules 75b are oriented
in random directions since they have been subjected to no
orientation processing. As a result, the refractive index of the
droplet becomes the average value between the ordinary refractive
index of the liquid crystal molecules 75b and the extraordinary
refractive index thereof, thus exceeding the refractive index of
the polymer film 75a. The difference in refractive index between
the droplet and polymer film 75a brings the polymer dispersion
liquid crystal layer 75 into a scattering state. Therefore, when
passing through the optical element 86, light entered into the
light beam direction regulating element 72 is scattered, so that
the outgoing light spreads. Furthermore, this light isotropically
scattered because the difference in refractive index is not
anisotropy. Hence, the spread of the outgoing light also becomes
isotropic.
On the other hand, as described with reference to FIG. 11B, upon
application of a voltage to the electrodes 74 and 76, the liquid
crystal molecules 75b in the droplets are oriented in the direction
of an electric field. That is, the major axes (having a direction
of extraordinary refractive index) of the liquid crystal molecules
75b are aligned with one another in the direction parallel to the
element normal direction (in the upward direction in the drawing).
In the element surface, therefore, the refractive index of the
liquid crystal molecules 75b becomes the ordinary refractive index
thereof, thus conforming to that of the polymer film 75a. This
brings the polymer dispersion liquid crystal layer 75 into a
transparent state. Consequently, the outgoing light from the light
beam direction regulating element 72 is not scattered when passing
through the optical element 86, so that the spread of light is
limited.
As in the fourth embodiment, use of an optical element formed by
enclosing a light adjusting material made by mixing a liquid
crystal and polymer material between a pair of substrates allows
switching the optical element between a transparent state and
scattering state by the switching between the state of applying a
voltage to the optical element through the external circuit and the
state of not doing so. This produces the effect of making variable
the lighting angle range of the light source unit.
Furthermore, constructions, operations, and effects other than the
foregoing in the fourth embodiment are similar to those in the
above-described first to third embodiments.
Fifth Embodiment
Now, a display device according to a fifth embodiment of the
present invention will be described.
The display device according to the fifth embodiment of the present
invention is characterized in that the above-described optical
element is stacked on a backlight emitting light, and a light beam
direction regulating element which regulates the direction of light
entered from the backlight and which emits the light, and that a
liquid crystal display device is further stacked on the optical
element. That is, the difference of the display device according to
the fifth embodiment from that of the fourth embodiment lies in
that the liquid crystal display device is stacked on the optical
element.
As shown in FIG. 10, the display device 150 is configured so that
the optical element 86 is stacked on the backlight 70 with the
light beam direction regulating element 72 therebetween, and that a
liquid crystal display element 85 formed by sandwiching liquid
crystal layer 81 between substrates 79 and 83 is stacked on the
optical element 86. In FIG. 10 also, components are separately
illustrated for easy understanding. On the substrates 79 and 83,
oriented films (not shown) for determining the oriented direction
of liquid crystal, and electrodes 80 and 83 for the purpose of
independently driving pixels are formed on the sides of liquid
crystal layer 81. Furthermore, absorptive polarizers 78 and 84,
respectively, are bonded to the surfaces of the substrates 79 and
83 (surfaces remote from the liquid crystal layer 81). Here, it is
preferable that the surfaces of the absorptive polarizers 78 and
84, especially the surface of the absorptive polarizer 84 be not
subjected to antiglare treating, which aims an antiglare effect by
scattering.
In FIG. 10, as the liquid crystal display element 85, a minimum
construction alone is shown for facilitating understanding of
effects of the fifth embodiment. The actual liquid crystal display
element, therefore, includes constituent elements other than those
shown in FIG. 10. Examples of constituent elements not shown in
FIG. 10 include a thin-film transistor (TFT), color filter, black
matrix, etc.
The liquid crystal display element 85 is changed in the orientation
of liquid crystal molecules by applying a voltage to the liquid
crystal layer 81. Polarized light that has passed through the
absorptive polarizer 78 is changed in a polarization state by a
birefringence effect or optical activity due to an orientation
change of liquid crystal molecules, and the amount of light passing
through the absorptive polarizer 84 changes. Here, the amount of
outgoing light is adjusted on a pixel-by-pixel basis, and thereby a
contrast adjustment of display is implemented.
The view angle characteristic of the liquid crystal display element
85 depends on a liquid crystal display mode. In order to realize a
wide view angle state and narrow view angle state as in the present
invention, it is preferable to adopt a wide view angle mode as a
liquid crystal display mode. Specifically, wide view angle modes
include lateral electric field mode such as an in-plane switching
(IPS) mode and fringe field switching (FES) mode for operating
liquid crystal molecules in a plane of the liquid crystal display
element 85 utilizing a lateral electric field; and a film
compensation modes such as a vertical alignment (VA) mode,
patterned vertical alignment (PVA) mode, and advanced super V (ASV)
mode for performing optical compensation using a vertical
orientation mode or anisotropic optical film.
Thereby, the view angle of the liquid crystal display element 85
can be switched between a narrow view angle state and wide view
angle state by switching the optical element between a transparent
state and scattering state using the liquid crystal display element
85 capable of a wide view angle display.
Next, description will be made of operations of the display device
according to the fifth embodiment, formed as described above. As
shown in FIG. 10, the light outgoing from the backlight 70 is
diffused light and has a wide angular distribution from the front
of the display device. The light outgoing from the backlight 70 is
limited in the angular range of outgoing light by the light beam
direction regulating element 72. Specifically, as shown in FIG. 10,
wide angle light out of the diffused light cannot pass through the
transmission region 72a, but is absorbed in the absorption region
72b. The light outgoing from the light beam regulating element 72
results in an outgoing light with high directivity.
Upon entering of this outgoing light into the optical element 86,
the incident light is isotropically scattered, since there is no
voltage applied to the optical element 86 as described with
reference to FIG. 11A. Therefore, the light outgoing from the
optical element 86 reduces in directivity, and has an isotropically
wide angular distribution.
As shown in FIG. 10, the outgoing light having isotropically spread
in a wide range enters the liquid crystal display element 85, and
is emitted with the angular distribution unchanged. Because the
liquid crystal display element 85 uses a liquid crystal in a wide
view angle mode, images are displayed at a wide view angle.
Next, the case of a narrow view angle is described. As in the case
of the wide view angle, light outgoing from the backlight 70 passes
through the light beam regulating element 72, and the outgoing
light with high directivity enters the optical element 86.
As described with reference to FIG. 11B, the optical element 86
comes into a transparent state by applying a voltage to the optical
element 86 serving as a transparence/scattering switching element,
and by orienting the liquid crystal molecules 75b. In this case,
incident light is emitted without being scattered. In other words,
the directivity of the light outgoing from the optical element 86
still remains high. This outgoing light with high directivity
enters the optical element 85, and is emitted with the angular
distribution unchanged. Thus, an image at a narrow view angle is
displayed.
As described above, with the arrangement according to the fifth
embodiment, the present invention allows the optical element to be
held in a narrow space while improving the yield of the optical
element. In addition, the optical element 86 can be switched
between a transparent state and scattering state by the switching
between the state of applying a voltage to the optical element 86
and the state of not doing so, whereby the liquid crystal display
device 85 is made variable in the lighting angle range of the light
source unit. This allows the switching between a wide view angle
display and narrow view angle display.
According to the present invention, there is further provided a
terminal device incorporating the above-described optical element,
a light source unit using this optical element, or a display device
using this light source unit, especially a hand held or portable
terminal.
FIG. 12 is an example in which the present invention is
incorporated especially into a mobile phone out of terminal
devices. As shown in FIG. 12, the mobile phone is configured so
that a reception unit 160 and transmission unit 170 are connected
at a hinge portion H. The reception unit 160 has a display device
150, and the transmission unit 170 has a plurality of key switches
180.
Having described the present invention as related to several
embodiments, it is to be understood that the optical element, light
source unit, display device, and terminal device according to the
present invention are not limited to the above-described
embodiments, but various changes and modifications may be made in
their constructions. Also it is to be understood that the optical
elements, light source units, display devices, and terminal devices
having subjected to such changes and modifications are also
included in the range of the present invention.
For example, as a substrate used for the optical element 86, not
only a transparent substrate, but also a substrate of which the
electrode connection portion is opaque, and a substrate of which
the display portion is partially opaque may be adopted.
Also, an optical element that is transparent when no voltage is
applied thereto, and that is in a scattering state when a voltage
is applied, may be used as the optical element 86. Thereby, the
lighting angle range of the light source unit or the view angle
range of the display device can be made variable by the switching
between the state of applying a voltage to the optical element and
the state of not doing so, as in the above-described
embodiments.
Moreover, as the optical element 86, a polymer dispersive liquid
crystal layer having memory capability may be used instead of the
polymer dispersive liquid crystal layer 75. In this case, the
liquid crystal polymer molecules 75b may include a ferroelectric
liquid crystal and cholesteric liquid crystal. Even when an applied
voltage is turned off, these liquid crystals retains their
orientation generated when a voltage was applied, thereby
presenting a memory capability. This brings the effect of reducing
power consumption.
According to the present invention, there is provided an optical
element in which a pair of substrates each having an electrode is
bonded together with a gap therebetween, and in which a light
adjusting material including at least a liquid crystal is enclosed
in the gap, each of the pair of substrates having an electrode
connecting portion to be connected to an external circuit. In
particular, the electrode connecting portions of both substrates
are located on the same side as that of the optical element; the
electrode connecting portion of one of the substrates and the
electrode connecting portion of the other of the substrates have
respective electrode portions at regions that are not opposed to
each other; and the electrode portion of each of the electrode
connecting portions is connected to the external circuit. This
makes it possible to improve the yield of the optical element while
ensuring its reliability, and store the optical element in a
space-saving manner, as well as drive the optical element.
* * * * *